Removable drive shaft unit for pulverizing mills



Nov. 30, 1948. w. A. GIBSON ET AL 2,454,863

' REMOVABLE DRIVE SHAFT UNIT FOR PULVERIZING MILLS Filed June 26, 1947 v 2 Sheets-$heet 1 NOV. 30, 1948. GIBSQN ET L 2,454,868

REMOVABLE DRIVE SHAFT UNIT FOR PULVERIZING MILLS Filed June 26, 1947 2 Sheets-sheaf. 2

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Patented Nov. 30, 1948 REMOVABLE DRI VESHAFT UNIT FOR PULVERIZING MILLS William A. Gibsonand Charles W. Mayer, Allen- I :town, Pa., assignors to Bradley Pulverizer Company, Boston, chusetts Mass, a corporation of Massa- Application June 26, 1947,;SerialNo. 757,236

4 Claims.

(01. o ens) This invention relates to pulverizin mills of the general class in which a vertically disposed center driving shaft carrying a series of crushing roll assemblies is driven from a horizontal drive shaft through the intermediary of a bevel pinion secured to the drive shaft and meshing with a bevel ring gear on the center shaft, both gears being enclosed within a gear chamber surmounting the machine frame. Examples of this general, type of mill are disclosed in Patent No. 1,655,499 of William A. Gibson, granted January 10, 1928, and Patent No. 1,690,125 of Charles E. Needham, granted November 6, 1928.

Heretofore in this class of pulverizing mill it has been necessary to virtually dismantle the upper portion of the mill structure in order to raise the ring gear along the center shaft a suflicient distance to allow the withdrawal of the drive shaft and pinion from the gear chamber. top of the gear chamber carries a centering bearing adapted to receive the upper end of the center shaft, the removal and consequent replacement of this closure is apt to result in misalignment of the center shaft which must be corrected before the mill can be restored to operation. Even under the most favorable circumstances the removal of the drive shaft from the mill, because of the huge and massive construction of mills of this kind, is a laborious and time-consuming task which necessitates shutting the mill down for an extended period of time, first to allow it to cool and then to make the necessary repairs. In the case of some mill installations the driving motor is fixedly mounted in line with the drive shaft which prohibits shifting of the drive axially for any considerable distance.

An important object of the present invention is to provide in a pulverizing mill of the above character an improved mounting for the drive shaft which overcomes the above objections and renders it comparatively easy to remove the drive shaft and pinion for repair or replacement without the need for tearing down the mill or placing it out of service for any great length of time. More especially this object is accomplished by providing a mounting such that the drive shaft and its pinion may be removed from-the mill without raising the bevel gear and hence without the need for disturbing the center shaft centering bearing 'orother operative parts of the mechanism. I I

Another object of the invention is to provide in a pulverizing mill of the above character a bearing box for the drive: shaft located contigue- Furthermore, because the closure for the ous to the" gear chamber. and adapted to seat a bearing cartridge encircling and providing the sole support for the pinion-carrying end of the drive shaft, the construction and arrangement being such that the drive shaft unit may be expeditiously removed through a suitably provided clearance opening at one side of the gear .charnber merely by uncovering the bearing box and a section of the closure for the gear chamber.

Still another object of the invention is to provide in a pulverizing mill of the above character an improved mounting for the drive shaft unitwhich includes a clearance space located below the pinion which allows the drive shaft to be swung in a vertical plane during its removal from the mill.

Other objects and advantages will be apparent from the following detailed description of a preferred embodiment of the invention, reference being had to the annexed drawings in which:

Figure 1 is a vertical cross-sectional view through the top portion of a pulverizing mill showing the bearing box for supporting the drive shaft unit and also showing the gear chamber which encloses the pair of intermeshing bevel gears interposed between the drive shaft and the center driving shaft;

Figure 2 is a plan view of the pulverizing mill shown in Fig. 1'; I

Figure 3 is a transverse cross-sectional view ,through the bearing box taken on the line 3-3 fF e- ;v

Figure 4 is a detail view in side elevation of a portion of the top of the pulverizing mill, more particularly showing the bearing box leading off from the gear chamber; and

-Figure 5 is a diagrammatic sketch indicating the manner in which the drive shaft is adapted to be removed fromthe mill.

The centrifugal pulverizing mill shown in the drawing the upper portion only being illustratedcomprises generally a horizontal drive shaft l passing through a bearing box 2 forming part of a casting 3 surmounting and closing the top of the pulverizing chamber and supported on the machine frame F. Interposed between ,,that end of the drive shaft which is located exteriorly of the mill and the armature shaft of an electric motor M (partially shown), is a flexible coupling t, including a removable spacer ring 3a, the motor M being fixedly positioned in line with the drive shaft l Upon the other end of the drive shaft which is located interiorly of the'mill is secured a bevel pinion 5 which meshes with the lower face of an overlying bevel ring gear 6 carried by a spider 7. This spider, in turn, is fastened to the upper end of a vertically disposed center driving shaft 8 and rests upon a roller bearing 9. The center shaft 8 at its upper end projects into ,and turns within a centering bearing 9a mounted in the top of the closure member for the gear chamber.

In pulverizing mills of the centrifugal type, the

center shaft adjacent its lower end carries a series of crushing roll assemblies which are hinged so as to swing outwardly under the action of centrifugal force and urge the rolls against a die ring when the center shaft-is rotated, the material to be crushed being fed between the rolls and the die ring to accomplish the reduction thereof. Because the crushing mechanismlforms no part of the present invention, its illustration and description have been omitted and reference is made to the above-identified patents of Gibson and Needham for a more detailed description of such mechanisms;

The casting 3 is hollow and forms .an annular housing or gear chamber ID for the bevel pinion and the bevel ring gear .6. The top of the housing is removable and is constituted of a domeshaped closure H (which carries the centering bearing 9a) secured to the circumferential wall lfia of the housing by means of bolts l2 passing through openings in peripheral fiangesformed on the abutting faces of this wall and closure. The housing is formed with a pocket 13 providing space for the bevel pinion 5 and including a sunken portion or well l3a below the pinion which extends a short distance outwardly beyond the housing and in line with the drive shaft.

A generally cylindrical cartridge l5 encircles the drive shaft I and contains a pair of roller bearings M in its opposite ends, which bearings directly and solely support the inner end of the drive shaft for rotation. The bearing box comprises a generally rectangular block l6 which constitutes an integral part of the casting 3, and traversing the length of this block is a semicylindrical channel leading radially outward from the housing in line with the pocket 13 for snugly seating the bearing. cartridge 15.

The side walls of the bearingbox 2, which at their inner ends join the circumferential wall of the housing 10, are cut away as indicated in Fig. 3 to form two countersunk seats 16a the faces of which upon opposite sides of the channel lie in a common horizontal plane. The'seats [6a are flanked by upwardly projecting portions "lb of the side walls the upper edges of which are disposed at an inclination, as best illustrated in Fig, 4. The block [6 at its base has laterally projecting flanges 16c and a downwardly-directed flange [6:1 by which the bearing box, as part of the casting 3, is fitted upon and bolted to the machine frame F.

A cover H of semi-cylindrical shape ispositioned open side down upon the block IS with its longitudinal edges flatly seating against the faces 56a of the block. The cover I! together with the block I6 thus constitutes the bearing box 2 which encircles the drive shaft 1 and completely encloses the bearing cartridge [5. Bolts SB pass through openings in a series of bosses 19 arranged in longitudinally spaced arrangement along opposite sides of the cover I! and these bolts screw into mating threaded openings tapped in the block it, thus allowing for the removal of the cover.

The dome shaped closure ll of thehousing ID is of sectional construction and comprises a removable segment 20 which is positioned so as to vertically overlie the pocket l3 occupied by the bevel pinion 5. The two sections of the closure are normally held in unitary assembly by means of 'bolts 2d passing through aligned openings in abutting flanges 22 on these sections. likewise a peripheral flange 20a on the closure section rests upon and is secured by means of bolts Zla to a. complementary flange l'la skirting the top of a vertical wall l'lb located at the inwardly disposed end of the bearing box H. The wall 4317 thus constitutes in effect a section of the of the housing l0 enclosing the gear cham- The outer end of the bearing box 2 is closed by aradial flange 15a on the corresponding end of the bearing cartridge 15 which overlaps the end of the block l6 and the bearing box cover IT. The cartridge is held in place by bolts 22a extending through openings in this flange and screwed into companion openings in the and faces "of both 'theblock and the bearing box cover.

A cap .23 bolted to the outer end face of the bearing cartridge provides a seat for .a packing member 2a encircling the drive shaft E, and houses a look not '25 on the drive shaft which abuts the end face of the outermost of the pair :of roller bearings 14.

By virtue of the construction which has been described, the drive shaft l with its pinion 5 and its bearing cartridge 45, together constituting the drive shaft unit, is capable of being readily removed from the pulverizing mill. To accomplish this removal the spacer ring 4a is removed and the drive shaft is disconnected from the flex ible coupling d. Then the segmental closure section '20 of the gear housing 19 and the bearing box cover 11 are both removed by detaching their holding bolts 2!, 2m, 18 and 22a. The portion of the closure 1! carrying the centering bearing 9 remains "in place so that the alignment of the center shaft 8 is undisturbed.

After removing the bolts 22a which clamp the outer end of the bearing cartridge to the block i5, the free 'end of the drive shaft 5 is swung upwardly in a vertical plane and simultaneously shifted axially which causes the bevel pinion 5 to lower "into the well we. The length of this well is such as to provide clearance for the out ward withdrawal of the pinion, as indicated in the diagrammatic view of Fig. 5, while at the same time allowing the drive shaft to clear the motor M. The drive shaft unit may now be lifted free of thevmachine, the removal of the closure section 28 providing sufficient clearance to allow the pinion to pass out of thegear housing. Another drive shaft unit kept handily available in the shop may be substituted for the one withdrawn and the operation of the mill may be resumed with comparatively little loss of time.

While we have described a preferred embodiment of our pulverizing mill, it is to be understood that various and reasonable changes in construction and design from those herein described and illustrated may-be made without departing from the spirit of the invention as defined by the following claims.

We claim:

1. A pulveriz'ing mill comprising a vertically disposed center shaft and a horizontal drive shaft, said drive shaft having abevel pinion operatively mounted upon the'centershaft, .a housing enclosing said ring gear and providing a gear chamber therefor, a closure for the top of the gear chamber, a centering bearing carried by said closure and encircling the upper end of the center shaft, said housing including a bearing box encircling the drive shaft and communicating at one end with the interior of the gear chamber, said bearing box having a removable cover closing its upper side and a clearance pocket located below said pinion and extending outwardly in line with the drive shaft, said pocket being so constructed and arranged as to afford withdrawal clearance for said pinion by simultaneously swinging the drive shaft upwardly and axially through the uncovered upper side of said bearing box.

2. A. pulverizing mill as set forth in claim 1 wherein the closure for the top of the gear chamber is of sectional construction, a section of said closure disposed beyond the centering bearing being removable and located in overlying relation with the pocket.

3. A pulverizing mill as set forth in claim 2 in which the removable closure section is detachably secured in contiguous and superposed relation with the removable cover.

4. A pulverizing mill comprising a vertically disposed center shaft and a horizontal drive shaft, said drive shaft having a bevel pinion cperatively engaging the underface of a bevel ring gear mounted upon the center shaft, a housing eni closing said ring gear and providing a gear chamber therefor, a closure for the top of the gear chamber, a centering bearing carried by said closure and encircling the upper end of the center shaft, said housing including a bearing box encircling the drive shaft and communicating at one end with the interior of the gear chamber, said bearing box comprising a block having a channel extending along its face adapted to provide a seat for a cylindrical bearing cartridge encircling the drive shaft and a removable cover providing a semi-annular recess adapted to seat upon the block and embrace the upper side of the bearing cartridge, said block having a clearance REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,89%,92'? Schmitter Jan. 17, 1933 2,143,968 Alden Jan. 17, 1939 2,327162 Drake s" Aug. 24, 19443 

